Compounds containing a pentalene unit and process for their preparation

Abstract

Compound containing a pentalene unit having general formula (I) wherein R.sub.1 and R.sub.2, equal to or different from each other, are selected from: linear or branched C.sub.1-C.sub.20, preferably C.sub.2-C.sub.12, alkyl groups, saturated or unsaturated, optionally containing heteroatoms, cycloalkyl groups optionally substituted, linear or branched C.sub.1-C.sub.20, preferably C.sub.2-C.sub.12, alkoxyl groups, saturated or unsaturated, optionally substituted; or the groups R.sub.1 and R.sub.2 can be optionally bound to each other so as to form, together with the carbon atoms to which they are bound, a cycle or a polycyclic system containing from 3 to 14 carbon atoms, preferably from 4 to 6 carbon atoms, saturated, unsaturated, or aromatic, optionally containing one or more heteroatoms such as, for example, oxygen, sulfur, nitrogen, silicon, phosphorous, selenium; R.sub.3 is selected from aryl groups optionally substituted, heteroaryl groups optionally substituted; n is 0 or 1; with the proviso that: when n is 0, X represents a covalent bond and Y represents a sulfur atom (S); when n is 1, X is equal to Y, and represents a CH group, or a nitrogen atom (N). Said compound containing a pentalene unit, as such or after suitable functionalization and polymerization, can be advantageously used in the construction of photovoltaic devices (or solar devices) such as, for example, photovoltaic cells (or solar cells), photovoltaic modules (or solar modules), on both rigid and flexible supports. Said compound containing a pentalene unit can also be advantageously used as a constitutive unit of luminescent solar concentrators (LSCs). Furthermore, said compound containing a pentalene unit can be advantageously used as precursor of monomeric units in the preparation of semiconductor polymers. ##STR00001##

Claims

1. A compound comprising containing a pentalene unit having a general formula (I): ##STR00011## wherein: R.sub.1 and R.sub.2, equal to or different from each other, are linear or branched C.sub.1-C.sub.20 alkyl groups, saturated or unsaturated, optionally containing heteroatoms, optionally substituted cycloalkyl groups, optionally substituted linear or branched C.sub.1-C.sub.20 alkoxyl groups, saturated or unsaturated; or R.sub.1 and R.sub.2 are optionally bound to each other so as to form, together with carbon atoms to which they are bound, a cycle or a polycyclic system comprising from 3 to 14 carbon atoms, wherein the cycle or the polycyclic system is saturated, unsaturated, or aromatic, and the cycle or the polycyclic system optionally comprises a heteroatom; R.sub.3 is an optionally substituted aryl group or an optionally substituted heteroaryl group; n is 0 or 1; with the proviso that: when n is 0, X represents a covalent bond and Y represents a sulfur atom (S); when n is 1, X is equal to Y, and represents a CH group or a nitrogen atom (N).

2. The compound according to claim 1, wherein: R.sub.1 and R.sub.2 are branched C.sub.2-C.sub.12 alkyl groups, and R.sub.1 is equal to R.sub.2; R.sub.3 is an optionally substituted heteroaryl group; n is 1; and X is equal to Y, and represents a CH group.

3. A process for preparing the compound according to claim 1, comprising: performing a reductive homocoupling reaction of a halogenated alkoxy-aromatic or alkoxy-heteroaromatic compound having a general formula (II): ##STR00012## wherein Z represents a halogen atom selected from the group consisting of bromine, chlorine, and iodine, wherein the reductive homocoupling reaction is performed in the presence of a catalyst comprising palladium in oxidation state 0 or +2.

4. The process according to claim 3, wherein the halogenated alkoxy-aromatic or alkoxy-heteroaromatic compound having the general formula (II) and the catalyst are employed in a molar ratio ranging from 100:0.1 to 100:6.

5. The process according to claim 3, further comprising: performing the process in the presence of a weak organic base selected from the group consisting of carboxylates of alkaline metals, carboxylates of alkaline-earth metals, carbonates of alkaline metals, carbonates of alkaline-earth metals, bicarbonates of alkaline metals, bicarbonates of alkaline-earth metals, and mixtures thereof.

6. The process according to claim 3, further comprising: performing the process in the presence of a weak organic base selected from the group consisting of carboxylates of alkaline metals, carboxylates of alkaline-earth metals, carbonates of alkaline metals, carbonates of alkaline-earth metals, bicarbonates of alkaline metals, bicarbonates of alkaline-earth metals and mixtures thereof, wherein the halogenated alkoxy-aromatic or alkoxy-heteroaromatic compound having the general formula (II) and the weak organic base are employed in a molar ratio ranging from 1:2.2 to 1:20.

7. The process according to claim 3, further comprising: performing the process in the presence of an organic reducing agent selected from the group consisting of hydroquinone, pyrocatechol, and para-hydroxyaminobenzene.

8. The process according to claim 3, further comprising: performing the process in the presence of an organic reducing agent selected from the group consisting of hydroquinone, pyrocatechol, and para-hydroxyaminobenzene, wherein the halogenated alkoxy-aromatic or alkoxy-heteroaromatic compound having the general formula (II) and the organic reducing agent are employed in a molar ratio ranging from 1:1.5 to 1:10.

9. The process according to claim 3, wherein the halogenated alkoxy-aromatic or alkoxy-heteroaromatic compound having the general formula (II) is employed at a molar concentration ranging from 0.1 mmoles to 10 mmoles.

10. The process according to claim 3, further comprising: performing the process in the presence of a polar aprotic organic solvent selected from the group consisting of diethyl ether (Et.sub.2O), tetrahydrofuran (THF), 1,4-dioxane, dimethylsulfoxide (DMSO), N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), and mixtures thereof.

11. The process according to claim 3, further comprising: performing the process in the presence of a polar aprotic organic solvent selected from the group consisting of diethyl ether, tetrahydrofuran, 1,4-dioxane, dimethylsulfoxide, N-methylpyrrolidone, N,N-dimethylformamide, and mixtures thereof, wherein a quantity of the halogenated alkoxy-aromatic or alkoxy-heteroaromatic compound having the general formula (II) is mixed with the dipolar aprotic organic solvent to result in a molar concentration in the solvent ranging from 0.05 mmoles to 2 mmoles.

12. The process according to claim 3, wherein the catalyst comprises a ligand selected from the group consisting of tri(t-butyl)phosphine, triphenylphosphine, tricyclohexylphosphonium tetrafluoroborate, 2-dicyclohexyl-phosphine-2′-(N,N-dimethyl-amino)biphenyl (DavePhos), di-t-butyl(methyl)phosphonium tetra-fluoroborate, tri-t-butyl(methyl)phosphonium tetra-fluoroborate, and mixtures thereof.

13. The process according to claim 3, further comprising: the catalyst comprising a ligand selected from the group consisting of tri(t-butyl)phosphine, triphenylphosphine, tricyclohexyl-phosphonium tetrafluoroborate, 2-dicyclohexyl-phosphine-2′-(N,N-dimethyl-amino)biphenyl, di-t-butyl(methyl)phosphonium tetra-fluoroborate, tri-t-butyl(methyl)phosphonium tetra-fluoroborate, and mixtures thereof, wherein the halogenated alkoxy-aromatic or alkoxy-heteroaromatic compound having the general formula (II) and the ligand are employed in a molar ratio ranging from 100:1 to 100:10.

14. The process according to claim 3, further comprising: performing the process at a temperature ranging from 80° C. to 170°.

15. The process according to claim 3, further comprising: performing the process for a time ranging from 12 hours to 72 hours.

16. A method comprising employing the compound according to claim 1 in constructing at least one selected from the group consisting of photovoltaic devices, solar devices, photovoltaic modules, and solar modules, on both rigid and flexible supports, wherein the compound according to claim 1 is optionally functionalized and polymerized.

17. A method comprising employing the compound according to claim 1 as a constitutive unit of luminescent solar concentrators (LSCs).

18. A method comprising employing the compound according to claim 1 as a precursor of monomeric units for preparing semiconductor polymers.

Description

EXAMPLE 1

Preparation of 4,5-bis(2-ethylhexyloxy)-2-bromoiodobenzene

(a) Preparation of 1,2-bis(2-ethylhexyloxy)benzene having Formula (a)

(1) ##STR00006##

(2) 2-ethylhexylbromide (Aldrich) (11.39 g; 59.0 mmoles) and potassium carbonate (Aldrich) (9.5 g; 69.0 mmoles) were added, in a two-necked Pyrex glass flask, under an inert atmosphere, to a solution of catechol (Aldrich) (2.5 g; 22.7 mmoles) in anhydrous N,N-dimethylformamide (Aldrich) (20 ml), and the temperature was brought to 95° C. After 18 hours, the reaction mixture obtained was poured into water and extracted with ethyl ether (Carlo Erba) (3×25 ml). The organic phase obtained was washed to neutrality with water (3×25 ml), and subsequently anhydrified on sodium sulfate (Aldrich): the residual solvent was removed by distillation at reduced pressure. The residue obtained was purified by elution on a silica gel chromatographic column [(eluent: n-heptane) (Carlo Erba)], obtaining 7.2 g of 1,2-bis(2-ethylhexyloxy)benzene (yield 95%).

(b) Preparation of 1,2-bis(2-ethylhexyloxy)-4-bromobenzene having Formula (b)

(3) ##STR00007##

EXAMPLE 1

(4) N-bromosuccinimide (NBS) (Aldrich) (3.9 g; 22.0 mmoles) was added, in a two-necked Pyrex glass flask, under an inert atmosphere, to a solution of 1,2-bis(2-ethylhexyloxy)benzene (7.4 g; 22.0 mmoles), obtained as described in (a), in 39 ml of anhydrous tetrahydrofuran (THF) (Aldrich): the solution obtained was left in the dark, under stirring. After 18 hours, the reaction mixture obtained was poured into water and extracted with ethyl ether (Carlo Erba) (3×25 ml). The organic phase obtained was washed to neutrality with water (3×25 ml), and subsequently anhydrified on sodium sulfate (Aldrich): the residual solvent was removed by distillation at reduced pressure. The residue obtained was purified by elution on a silica gel chromatographic column [(eluent: n-heptane) (Carlo Erba)], obtaining 7.5 g of 1,2-bis(2-ethylhexyloxy)-4-bromobenzene (yield 83%).

(c) Preparation of 1,2-bis(2-ethylhexyloxy)-4-bromo-5-iodobenzene having Formula (c)

(5) ##STR00008##

(6) N-iodosuccinimide (NIS) (Aldrich) (4.7 g; 20.9 mmoles) was added, in a two-necked Pyrex glass flask, under an inert atmosphere, to a solution of 1,2-bis(2-ethylhexyloxy)-4-bromobenzene (7.5 g; 18.2 mmoles), obtained as described in (b), in 18 ml of chloroform (Carlo Erba) and 18 ml of acetic acid (Carlo Erba): the solution obtained was left in the dark, under stirring. After 12 hours, the reaction mixture obtained was poured into water and extracted with dichloromethane (Carlo Erba) (3×25 ml). The organic phase obtained was washed first with an aqueous solution of sodium thiosulfate 0.1 N (Aldrich) (3×25 ml), then with water (3×25 ml), subsequently with a saturated aqueous solution of sodium bicarbonate [NaHCO.sub.3(sat.)] (prepared with sodium bicarbonate of Aldrich) [NaHCO.sub.3(sat.)] (3×25 ml), and finally to neutrality with water, and subsequently anhydrified on sodium sulfate (Aldrich): the residual solvent was removed by distillation at reduced pressure. The residue obtained was purified by elution on a silica gel chromatographic column [(eluent: n-heptane) (Carlo Erba)], obtaining 6.7 g of 1,2-bis(2-ethylhexyloxy)-4-bromo-5-iodobenzene (yield 68%).

ESEMPIO 2

Preparation of 4,5-bis(2-ethylhexyloxy)-1-bromo-2-(2-(2-thienyl)ethinyl)benzene having Formula (IIa)

(7) ##STR00009##

(8) The following products were charged, in order, under an inert atmosphere, into a tailed Pyrex glass test-tube equipped with a screw stopper: 540 mg of 4,5-bis(2-ethylhexyloxy)-2-bromoiodobenzene (1.0 mmoles) obtained as described in Example 1, 150 mg of 2-[trimethylsilyl(ethinyl)]thiophene (0.83 mmoles) (Aldrich) dissolved in 5 ml of N,N-dimethylformamide (Aldrich), 35 mg of bis(triphenylphosphine)-palladium(II)chloride [Pd(PPh.sub.3).sub.2CH.sub.2] (Aldrich) (0.05 mmoles), 2 mg of copper(I)iodide (CuI) (Aldrich) (0.01 mmoles), 304 mg of triethylamine (Aldrich) (3.0 mmoles) and finally 379 mg of tetra-n-butylammonium fluoride (Aldrich) (1.0 mmoles). After closing the reactor, this was placed in an oil bath preheated to 50° C., for 4 hours. After cooling to room temperature (25° C.), an aqueous solution of hydrochloric acid 0.1 M (Aldrich) (50 ml) was added to the reaction mixture and the whole mixture was extracted with diethyl ether (Carlo Erba) (3×25 ml). The organic phase obtained was washed to neutrality with water (3×25 ml), and subsequently anhydrified on sodium sulfate (Aldrich) and evaporated. The residue obtained was purified by elution on a silica gel chromatographic column [(eluent: heptane) (Carlo Erba)], obtaining 425 mg of 4,5-bis(2-ethylhexyloxy)-1-bromo-2-(2-(2-thienyl)ethinyl)benzene as a yellow oil (yield 99%).

ESEMPIO 3

Preparation of 5,10-dithienyl-2,3,7,8-tetra(2-ethylhexyloxy)indeno[2,1-a]indene having Formula (Ia)

(9) ##STR00010##

(10) The following products were charged, in order, under an inert atmosphere, into a tailed Pyrex glass test-tube equipped with a screw stopper: 326 mg of caesium carbonate (Cs.sub.2CO.sub.3) (Aldrich) (1.0 mmoles), 111 mg of hydroquinone (Aldrich) (1.0 mmoles), 167 mg of caesium fluoride (CsF) (Aldrich) (1.1 mmoles), 6.07 mg of tri(t-butyl)phosphine [P(tBu).sub.3] (Aldrich) (0.03 mmoles), 6.87 mg of tris(dibenzylidene-acetone)palladium(0) [Pd.sub.2(dba).sub.3 wherein dba=C.sub.6H.sub.5CH═CHCOCH═CHC.sub.6H.sub.5] (Aldrich) (0.0075 mmoles) and finally 260 mg of 4,5-bis(2-ethylhexyloxy)-1-bromo-2-(2-(2-thienyl)ethinyl)benzene (IIa), obtained as described in Example 2, dissolved in 5 ml of 1,4-dioxane (Aldrich). After closing the reactor, this was placed in an oil bath preheated to 130° C., for 24 hours. After cooling to room temperature (25° C.), a saturated solution of sodium chloride [NaCl.sub.(sat.)] (prepared with sodium chloride of Aldrich) [NaCl], was added to the reaction mixture and the whole mixture was extracted with diethyl ether (Carlo Erba) (3×25 ml). The organic phase was subsequently anhydrified on sodium sulfate (Aldrich) and evaporated. The residue obtained was purified by elution on a silica gel chromatographic column [(eluent: heptane) (Carlo Erba)], obtaining 242 mg of 5,10-dithienyl-2,3,7,8-tetra(2-ethylhexyloxy)indeno-[2,1-a]indene as a red solid (yield 55%).